The aim of the invention is to detect content needed by a given application, whose implementation (hereafter the test device) is available as a “black-box” (i.e., a device that can be analysed externally by observing its reaction (output R) to different inputs I1, . . . In).
One particular field of application is Pay-TV field in which the content plays the role of security messages and the data stream is the video data broadcast by a satellite.
Some pirates use a satellite ISP or private satellite connection to broadcast via satellite the control words “CWs” (which are one example of the security messages) protecting a payTV operator's content. The control words are extracted from a genuine security module and spread to users having subscribed to this pirate service.
The Satellite Key Sharing pirate STBs or dongles will then only need satellite feeds to get either the video scrambled and the CW to descramble. The pirate decoder receives the audio/video stream in the same manner as the genuine user i.e., through satellite or terrestrial signal and connects in parallel their decoder to this CW stream service. The control word is then passed to the decoder to decrypt the audio/video content and to obtain the audio/video in clear. Each control word is used to encrypt a part of the audio and video stream (A/V stream). A slice of NV stream encrypted with the same control word composes a crypto period.
Pirates may change the satellite ISP or private satellite connection very often, so identification of the pirate feed requires fast and automatic tools.
Furthermore, to identify illicit CWs within the satellite streams, the analyzing tools need to access to the satellite beams' footprint.
Depending on the location of the footprint and of the personnel performing the analysis operations, limited internet connectivity may be available between the two, hence requiring optimized solutions to reduce traffic.
As it is well known, in such Pay-TV systems that use a security module, the content is encrypted by means of control words and is then sent to multimedia units connected to a data or content supplier. The controls words are sent to multimedia units in an encrypted form in control messages (ECM). These control messages (ECM) are transmitted by the decoder of the multimedia unit to the security module of this unit. If the decryption rights are present, the control messages are decrypted in order to extract the control words. Said control words are returned to the decoder that uses them to decrypt the content.